Imported infected cucurbit seeds provoked the establishment and spread of central Europe isolates of Zucchini yellow mosaic virus in Varamin (Sothern Tehran, Iran)

Zucchini yellow mosaic virus (ZYMV) is one of the most important viruses infecting cucurbits and the epidemiology of the virus is of considerable practical significance. The coat protein (CP) of Potyviruses is a phylogenetically informative sequence, but there is no ZYMV-CP sequence available from Varamin, an important cucurbit producing region. Therefore, the aim of this study was isolating the ZYMV-CP gene in Varamin isolates and studying its phylogenetic relationship(s) with previously reported ZYMV isolates. To this end, melon leaf samples were collected from Varamin, Pishva and Pakdasht (Southern Tehran) during the spring and summer of 2014-2015. ZYMV was detected in 34% of the collected samples. Sequencing data showed ZYMV-CP in the Varamin isolate was 840 nucleotides in length. Phylogenetic trees based on the entire ZYMV-CP gene showed all the ZYMV isolates cold be placed in three main groups A, B and C in which group A was further subdivided into 8 subgroups, A1-A8. Iranian isolates of ZYMV are placed in A1, A6 (including the Varamin isolate) and A8 subgroups. Subgroups A7 and A8 were detected for the first time in this study. However, in the N-terminal region of the CP, the most variable region, central Europe isolates harbor a landmark conserved motif of N16N17A27M37. This motif was detected in the ZYMV-Varamin isolate but not in other Iranian isolates, suggesting that this isolate might have been imported from central Europe by means of infected cucurbits seeds.